html, body{
  margin: 0;
  padding: 0;

  ul{
    list-style: none;
    padding: 0;
    margin: 0;
    
    li{
      font-size: 12px;
      line-height: 30px;
      padding-left: 10px;
    }
  }

  .box{
    width: 500px;
    height: 230px;
    background: url('../images/开心.gif');
    background-size: cover;
  }
}